At this years new year open day they announced the Custodes codex with a video showing the new models, and announced the Thousand Sons dex and the Legions of Nagash battletome.
While I agree there probably won't be anything AoS now til January, 40kQuest is out this month, and the LOTR release isn't gonna be that big (old models re-released, the Hobbit book is through Forge World).
Archaons never really been the strongest chaos character. He’s not the Everchosen purely on physical strength, plus he has the backing of all the gods not just 1 like this guy.